1. Field of the Invention
This invention relates to an electric double-layer capacitor.
2. Description of the Related Art
Electric double-layer capacitors are used as auxiliary power sources configured to supply electric power to memories, real time clocks (RTC), and other components that are mounted on industrial machines or consumer electronics, for example. When being mounted by reflow soldering, the electric double-layer capacitor is exposed to high temperature. When a mold resin is used as an exterior material for the electric double-layer capacitor, an electrolytic solution is boiled with heat in reflow soldering and an internal element expands, with the result that the mold resin is sometimes damaged. To cope with this, there have been proposed electric double-layer capacitors having various structures that improve high-temperature resistance of the electric double-layer capacitors.
In Japanese Patent No. 3023627, there is disclosed an electric double-layer capacitor that includes a hook-like terminal for positive and negative electrode plate lead terminals. In the electric double-layer capacitor disclosed in Japanese Patent No. 3023627, the hook-like terminal is provided to one of the positive and negative electrode plate lead terminals, and the other electrode plate lead terminal is sandwiched with the hook-like terminal so that holding force for an element is maintained.
However, the related-art electric double-layer capacitor, in which distances between the electrode plate lead terminals and the exterior wall made of a mold resin vary from place to place, has a possibility that stress concentrates on the part in which the distance is short when the internal element expands in reflow soldering, resulting in a reduction in mechanical strength. For example, Japanese Patent No. 3023627, in which the end portion of the hook-like terminal, which is provided to the electrode plate lead terminal, wraps around to the back surface of the other electrode plate lead terminal, has the following problem. Specifically, the end portion of the hook-like terminal causes stress concentration on the thin exterior of the back surface of the electrode plate lead terminal when the internal element expands in reflow soldering, resulting in a reduction in mechanical strength.
The configuration of Japanese Patent No. 3023627 also has a problem of complicated assembly of the structure in which the electrode plate lead terminal is sandwiched with the hook-like terminal so that the element is compressed in order to prevent the expansion of the internal element.